package com.day19.exer;

import org.junit.Test;

public class StringDemo2 {
    /*
    获取两个字符中最大相同子串。比如：
    str1=“abcwerthelloyuiodefabcdef”;str2=“cvhellobnm”
    提示：将短的那个串进行长度依次递减的子串与较长的串比较
     */
    //前提：两个字符串中只有一个最大相同子串
    public String getMaxSameString(String str1,String str2){
        if(str1 != null && str2 != null){
            String maxStr = (str1.length() >= str2.length())? str1 : str2;
            String minStr = (str1.length() < str2.length())? str1  : str2;
            int length = minStr.length();

            for(int i = 0;i < length;i++){

                for(int x = 0,y = length - i;y <= length;x++,y++){
                    String subStr = minStr.substring(x,y);
                    if(maxStr.contains(subStr)){
                        return subStr;
                    }
                }
            }
        }
        return null;
    }

    //如果存在多个长度相同的最大相同子串
    //此时先返回String[]，后面可以用集合中的ArrayList替换，较方便
    public String[] getMaxSameString1(String str1,String str2){
        if(str1 != null && str2 != null){
            StringBuffer sBuffer = new StringBuffer();
            String maxString = (str1.length() > str2.length())? str1 : str2;
            String minString = (str1.length() > str2.length())? str2 : str1;

            int len = minString.length();
            for(int i = 0;i <len;i++){
                for(int x = 0,y = len - i;y <= len;x++,y++){
                    String subStr = minString.substring(x,y);
                    if(maxString.contains(subStr)){
                        sBuffer.append(subStr + ",");
                    }
                }
//                System.out.println(sBuffer);
                if(sBuffer.length() != 0){
                    break;
                }
            }
            String[] split = sBuffer.toString().replaceAll(",$","").split("\\,");
            return split;
        }
        return null;
    }

    @Test
    public void testGetMaxSameString(){
        String str1 = "abcwerthelloyuiodefabcdef";
        String str2 = "cvhellobnmabcdef";

        String maxSameString = getMaxSameString(str1,str2);
        System.out.println(maxSameString);
//        String[] maxSameStrings = getMaxSameString1(str1,str2);
//        System.out.println(Arrays.toString(maxSameStrings));
    }
}
